2D C‐Axis‐Aligned Crystalline In─S─O Transistors Processed from Aqueous Solution

Abstract There is a growing interest in exploring nanometer‐thin 2D oxide semiconductor transistors for future scaled and multifunctional (e.g., ultraflexible and high transparency) devices. However, further development is hindered due to the degraded device performance with nanometer‐thin 2D oxide semiconductor channels and the use of costly vacuum‐based techniques. Here, 2D (2.7 nm thick) c‐axis‐aligned crystalline In─S─O channel material processed from aqueous solution is reported. The 2D In─S─O transistors based on Si/SiO2 substrates exhibit high mobility (µ) of 22.15 cm2 V−1 s−1, on/off current ratio (Ion/Ioff) of ≈107, and good bias stress stability. Detailed investigations show that this achievement is attributed to the highly c‐axis‐aligned crystalline structure, well‐designed In─S─O channel material, and atomically smooth surface. Furthermore, the 2D In─S─O channel is integrated with an aqueous sol‐gel‐derived 6 nm thick high‐k ZrO2 insulator. The all‐aqueous‐solution‐based quasi‐2D In─S─O/ZrO2 devices show high µ of 15.65 cm2 V─1 s─1, Ion/Ioff of ≈106, and low operating voltage of 1.5 V. This 2D c‐axis‐aligned crystalline wide‐bandgap oxide semiconductor channel material opens tremendous opportunities for multifunctional, ultra‐scaled and low‐cost electronics.